The most common standard door hinge is a butt hinge which comprises two plates or leaves hingedly attached to each other about a single pivot point or axis. A typical prior art butt hinge 100 is shown in FIG. 1A and comprises a door side leaf 102 and a jamb side leaf 104. The door side leaf 102 is typically mortised into a heel or edge 110 of the door 106 and the jamb side leaf 104 is typically mortised into jamb 108 of the doorway. Each of the leaves 102, 104 are further provided with a plurality of apertures (not shown) for passage of screws therethrough in order to attach the door side leaf 102 to the door heel or edge 110 and the jamb side leaf 104 to the door jamb 108. The leaves 102, 104 each have one or more rolled, tubular segments or knuckles (not shown) along a side edge. The knuckles of each leaf 102, 104 are specifically sized and arranged so as to mesh in axial alignment with the knuckles of the other leaf, thereby forming a hinge bone. A pin 112 is inserted through the axially aligned knuckles to effectively couple the leaves 102, 104 so that they are movable relative to one another about a common axis, defined by the hinge pin 112.
A problem with the standard butt hinge 100 is that when the door 106 is open at a 90 degree angle as shown in FIG. 1A, the entire door 106 is in the doorway thereby cutting down the available width or access through the doorway clearance space. The doorway clearance space 107 is generally defined as the space between two parallel planes 109, wherein each plane 109 is co-planar to a corresponding front face 111 of a door stop 113 on either side of the doorway as best shown in FIG. 1B. The problem is further accentuated by the fact that it is preferred in architectural design to place doorways near a corner of the room in order to cut down on lost room/wall available space, promote airflow in the structure, etc., as shown in FIG. 1B. The result is that the hinge side of the doorway may have a wall 130 perpendicular to the doorway wall 128 which limits the door movement to significantly less than the 180 degrees needed to clear the door 106 from the doorway clearance space 108. This requires that the door 106 is removed from the doorway by disconnecting all the hinges 100 any time furniture or other larger objects are needed to be moved through the doorway. Another resulting problem is that the standard butt hinge 100 allows the door to swing freely regardless if there is a wall in the path of the door 106. In order to prevent the door handle from damaging a perpendicular wall 130, a door stop must be added to the wall 130 or to the door hinge 100 to limit the movement of the door 106. Door stops are generally not aesthetically pleasing, may damage the door, add cost to procure and install, and may present a hazard protruding from the wall when the door is closed.
One attempt to solve the door clearance problem is the swing away or offset hinge. The offset hinge also comprises two leaves in the form of brackets hingedly attached to each other about a single pivot point such that the brackets nest in each other when the door is closed. As shown in FIG. 2, the offset hinge 120 has a pivot point formed by the hinge pin 112 which is significantly offset away from the door jamb 108. When the door is opened at 90 degrees, the door is no longer in the doorway clearance space 108. However, several problems with the offset hinge 120 have prevented the use of the offset hinge 120 in most applications other than hospitals and other functional based environments. The offset hinge 120 is not aesthetically pleasing. The bracket leaves 122, 124 must extend completely over the casing of the doorway in order to enable the door to swing out of the passageway. The operation of the brackets 122, 124 place the door 106 at a significant distance from the doorway when the door 106 is opened at 90 degrees. This results in large moment, compressive, and tensile forces acting on the hinges 120 due to the weight and position of the door 106. This requires that the brackets 122, 124 are oversized to compensate for the strength requirement, or that additional hinges 120 are used to mount the door 106. Reinforcement of the wall may be required to support the hinge and door. In addition, the entire surface of both bracket leaves 122, 124 are visible when the door is opened making the offset hinge 120 even more aesthetically unpleasing and is a potential hazard to children. Another problem with the offset hinge 120 is that, like the standard butt hinge 100, the door 106 is able to swing freely regardless if there is a wall in the path of the door 106. Accordingly, a door stop must be added to the wall or to the offset hinge 120 to limit the movement of the door 106.
In view of the above noted problems as well as other problems associated with prior art hinges, there remains a need in the art for an aesthetically pleasing hinge assembly which moves the door out of the doorway when the door is opened at a 90 degree angle.